1. Field of the Invention
The present invention relates to probes that may be used to dispose gas sensors within boilers, furnaces, or other combustors.
2. Discussion of Related Art
In numerous industrial environments, a hydrocarbon fuel is burned in a combustor (e.g., a boiler or furnace) to produce heat to raise the temperature of a fluid. The fluid may, for example, be water which is heated to generate steam to drive a turbine generator that provides power. Such industrial combustors typically employ an array of many individual burner elements to combust the fuel. In these combustors, various post-flame combustion control systems, such as overfire air, staging air, reburning systems, and selective non-catalytic reduction systems, can be employed in the post-flame zone to enhance the efficiency of the combustor. For the combustor to operate efficiently and to produce an acceptably complete combustion having byproducts that fall within the limits imposed by environmental regulations and design constraints, all of the individual burners should be operating cleanly and efficiently, and all post-flame combustion control systems should be properly balanced and adjusted.
Emissions of unburned carbon, nitrous oxides, carbon monoxide or other byproducts commonly are monitored to ensure compliance with environmental regulations. The monitoring of emissions heretofore has been done, by necessity, on the aggregate emissions from the combustor (i.e., the entire burner arrayxe2x80x94taken as a whole). Some emissions, such as the concentration of gaseous combustibles in hot flue gases, are difficult and/or expensive to monitor on-line and continuously. These emissions are typically measured on a periodic or occasional basis. When a particular combustion byproduct is found to be produced at unacceptably high concentrations, the combustor should be adjusted to restore proper operations. However, measurement of aggregate emissions, or measurement of emissions on a periodic or occasional basis, provides little, if any, useful information regarding what particular combustor parameters should be changed to effect such an adjustment.
According to one aspect of the present invention, a gas-sensing probe for use in a combustor includes an elongated support member, a housing, a gas sensor, and sensor wires. The housing is attached to a distal end of the support member. The gas sensor is rigidly supported within the housing and is configured and arranged so as to be in fluid communication with an environment external to the housing. The sensor wires extend between the gas sensor and a proximal end of the support member and are configured and arranged such that the sensor wires are not caused to break by elongation of the support member due to thermal expansion and resulting movement of the gas sensor away from the proximal end of the support member because of the gas sensor being rigidly supported within the housing.
According to another aspect of the invention, a gas-sensing probe for use in a combustor includes an elongated support member, a housing, and a gas sensor. The housing is removably attached to a distal end of the support member, and the gas sensor is disposed within the housing and is configured and arranged so as to be in fluid communication with an environment external to the housing when in use in the combustor. The gas sensor and housing are removable from the distal end of the support member as a unit to facilitate replacement of a faulty gas sensor.
According to another aspect of the invention, a gas-sensing probe includes an elongated support member, a gas sensor, and a calibration tube. The gas sensor is supported by a distal end of the support member, and the calibration tube extends along a length of the support member. The calibration tube has a first opening near a proximal end of the support member and a second opening, in fluid communication with the first opening, near the distal end of the support member and the gas sensor.
According to another aspect of the invention, a method for calibrating a gas sensor disposed in the post-flame zone of a combustor involves calibrating the gas sensor when the gas sensor is disposed in the post flame zone of the combustor.